Transformer slide switch with contact clamping means

ABSTRACT

An electrical series-multiple switch adapted for mounting within the casing of an electrical transformer, and actuable from without the casing. The switch, which may be used for single or polyphase applications, includes at least one cooperative pair of insulating shaft members, which carry a plurality of complementary electrical contacts spaced across the longitudinal dimensions of the shaft members. One of the pair of insulating shaft members is movable rectilinearly, relative to the other, in response to rotary movement of an operating shaft, which changes the relationship of the electrical contacts and the operating position of the switch.

I Ullltfll States Patent 1 51 3,673,364

Klein June 27, 1972 (54] TRANSFORMER SLIDE SWITCH WITH 3,192,323 6/1965 Wi1son,Jr. ..200/11 B CONTACT CLAMPING MEANS 3,045,090 7/1962 Wilson,Jr. et al... .200! B X 3,244,966 4/1966 Gertsch et al 200/11 TC X {721 K 3,396,248 8/1968 Wilson, Jr ..20o/11 TC [73] 3:2??? FOREIGN PATENTS 0R APPLICATIONS [22] Filed: Nov. 3, 1970 448,390 8/1927 Germany ..200/l6 F [21] App]. No.: 89,397 Primary Examiner-J. R. Scott Attorney--A. T. Stratton, F. E. Browder and D. R. Lackey I52] [1.5. CI. ..200/l6 C, 200/16 F 57 ABSTRACT [51] Int. Cl .........H0ll| 15/08,H0lh I156 [58] Field olSearch ..200 11 R, 11 B, 11 TC, 16 R, An electrical mks-multiple switch adapwd fm mounlins 200/16 F, 16 C within the casing of an electrical transformer, and actuahle from without the casing. The switch, which may be used for [56] References m single or polyphase applications, includes at least one cooperative pair of insulating shaft members, which carry a UNITED STATES PATENTS plurality of complementary electrical contacts spaced across the longitudinal dimensions of the shaft members. One of the 3221' 12/1966 Ge'ardm et "200/ C x pair of insulating shaft members is movable rectilinearly, rela- 9 11 1901 Scott ..200/16 F We m the other, in response to Mary movement of opmb 25021438 4,1950 Deakm ing shaft, which changes the relationship of the electrical con- 255032' H Greene tacts and the operating position of the switch. 2,412,604 12/1946 Dolan ..200,'l6 F 1,089,564 3/19 I4 H011 ..200/l6 F 5 Claims, 7 Drawing Figures PATENTEDJURZT m2 3. 673 364 sum 1 or 4 FIG. I.

WITNESSES INVENTOR I Kenneth R. Klein '7 22514 Jazz/(Q, Z4 4 ATTORNEY PATENTEDJUHZT I972 3,673 .364

sum 20F 4 TRANSFORMER SLIDE SWITCH WITI'I CONTACT CLAMPING MEANS BACKGROUND OF THE INVENTION I. Field of the Invention The invention relates in general to electrical switches, and more specifically to electrical series multiple switches adapted for mounting within the casing of an electrical transformer.

2. Description of the Prior Art Many transformers are purchased by electrical utilities with series-multiple switches, which are no-load switches disposed within the transformer tank or casing, and connected to certain windings or coil sections of the transformer, which are connected either in series, or in parallel, depending upon the operating position of the switch. Thus, the electrical utility is free to readily change the magnitude of the primary voltage applied to the transformers in the future, without the necessity of changing all of the transformers connected to the system. Since the series-multiple switch is operated only at the time of a system voltage changeover, it is a no-load type switch, and although it does not have to be constructed to allow a large number of mechanical operations, it must be extremely reliablc.

The different system voltages of the electrical utilities, along with the different preferences of the utilities, have resulted in a large number of different series-parallel circuit arrangements. For example, a single-phase application, or each phase of a polyphase application, may interconnect two separate coils, one with a tap, or three separate coils without taps, or three separate coils with one having a tap, with some of the tapped three coil arrangements requiring a three position switch instead of the conventional two position switch. Further, some arrangements have no protective links, others have two, and still others have four. The series-multiple switch should be versatile enough to accommodate these arrange ments, single or polyphase, without unduly complicating the switch and without an increase in manufacturing cost which would offset any potential savings a versatile switch would offer.

In the prior art, the series-rnultiple switches often become complicated when extended to polyphase service. For example, a plurality of single-phase switches may be interconnected by mechanical linkage members which are dil'ficult to properly adjust, and which may require the casing size to be increased just to accommodate the bulky assembly.

Thus, it would be desirable to provide a rugged, reliable series-multiple switch which may be manufactured for a rela tively low cost, which is easily mounted within the casing of an electrical transformer without the necessity of providing a larger tank or casing than would otherwise be required, and which is equally suitable for single or polyphase applications without the necessity of mechanically ganging or interconnecting a plurality of single'phase switch structures via bulky linkage members.

SUMMARY OF THE INVENTION Briefly, the present invention is a new and improved series multiple switch which includes at least one pair of insulating shaft members, disposed in spaced, parallel relation. The spaced insulating shaft members carry complementary electrical contact members which engage and disengage as one shaft member is moved rectilinearly along its longitudinal axis, providing the required number of switch positions at predetermined different stops. The switch is disposed inside the casing of its associated electrical transformer, with the electrical contacts disposed below the level of the insulating and cooling liquid disposed in the casing, and having an operating handle extending in sealed relation through the wall of the casing. Rotary movement of the operating handle actuatcs a pinion gear engaged with gear teeth disposed on the movable insulating shaft member, imparting rectilinear movement to the shaft through the rack and pinion type assembly when it is desired to change the relationship of the electrical contact members on the cooperatively spaced insulating shah members.

Polyphase operation of the switch is easily achieved by selecting the required length for the insulating shaft members, and providing the insulating shaft members with the required number of electrical contact members. While polyphase applications extend the length dimension of the switch, the crossscctional area required by the switch is very small, and the length dimension, instead of being a detriment, provides the advantage of reducing the length of the electrical leads from the windings to the switch. The switch is mounted immediately adjacent to the plurality of electrical coils or windings to be connected thereto, either horizontally or vertically, depending on the arrangement of the magnetic core-winding assembly, which not only shortens the length of the leads required, but facilitates the connection of the electrical leads to the switch, as they are spread out and not all brought to the same location, such as would be required by a ganged rotary type switch. Further, the in-line construction of the series multiple switch makes it easier to meet the required voltage and current rating of the switch, than it would be, for example, with a rotary type switch, as providing the required electrical clearance between adjacent contacts merely extends one dimension of the ln-line switch, while increasing the clearance between contacts on a rotary deck, and between adjacent rotary declts, increases the dimensions of the switch in three directions.

BRIEF DESCRIPTION OF THE DRAWINGS The invention may be better understood, and further advantages and uses thereof more readily apparent, when considered in view of the following detailed description of exemplary embodiments, taken with the accompanying drawings, in which:

FIG. I is an elevational view, partially cutaway, of an electrical transformer having a series-multiple switch constructed according to the teachings of the invention;

FIG. 2 is a perspective view of the series-multiple switch shown in FIG. 1;

FIG. 2A is an exploded perspective view of one of the electrical contact structures of the series-multiple switch shown in FIG. 2;

FIG. 3 is a diagrammatic representation of the series-multiple switch shown in FIGS. 1 and 1, illustrating parallel connection of a TT connected transformer;

FIG. 4 is a schematic diagram of the windings of the TT connected transformer shown in FIG. 3, as connected by the position of the series-multiple switch shown in FIG. 3;

FIG. 5 is a diagrammatic representation of the series-multiple switch shown in FIG. 3, illustrating another operating posi tion of the switch which connects the windings of the T-T connected transformer in series; and

FIG. 6 is a schematic diagram of the windings of the TT connected transformer shown in FIG. 3, as connected by the position of the seriessmultiple switch shown in FIG. 5.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings, and FIG. I in particular, there is illustrated an electrical transformer 10 of the distribution type, shown partially cut-away in order to reveal an internally mounted series-multiple switch 12, constructed according to the teaching; of the invention. Transformer 10 includes a magnetic core-winding assembly 14 disposed in a tank or casing 16 having side wall, bottom, and top portions ll, 13 and 15, respectively, which is fllled to a predetermined level 1! with a suitable insulating and cooling liquid dielectric, such as mineral oil. A plurality of high voltage bushings 19, 20 and 21, and a plurality of low voltage bushings shown generally at 22, are disposed on the top or cover 15 and side wall portions 1 1, respectively, of casing 16, which insulate and seal the con' nections of the high and low voltage windings of the transformer 10 to external electrical power and load circuits, respectively.

Transformer 10 may be single or polyphase, and for purposes of example is illustrated as being of the TT or Scott connected type for economically effecting three-phase transformations. The magnetic core-winding assembly 14 includes first and second single-phase assemblies 24 and 26, each of which include a magnetic core assembly, a low voltage winding, and a plurality of high voltage winding sections which are connected either in series or in parallel through the series multiple switch 12, as required by the electrical utility to match their existing and proposed future transmission voltages. In this example, the two single-phase assemblies 24 and 26 are mounted vertically one above the other, and supported by a U-frame 28, but they may also be mounted side-by-side, if desired.

As illustrated more clearly in FIG. 2, which is a perspective view of the seriesmultiple switch 12 shown in FIG. 1, switch 12 includes first and second spaced support means 30 and 32, respectively, which are preferably formed of a non-magnetic metal, such as brass or aluminum. Series-multiple switch 12 includes at least one insulating shaft member permanently fixed to the first and second support means 30 and 32, and for purposes of example, two insulating shaft members 34 and 36 are illustrated pennanently fixed to the support means, such as by bolts 49. The shaft members 34 and 36, as illustrated, may have two flat, major opposed sides or surfaces, which are joined by two flat opposed minor sides or surfaces. The number of permanently fixed insulating shaft members is determined by the number of winding sections to be interconnected, the voltage and current rating of the switch, and the maximum allowable length dimension of the switch 12.

Since the transformer l shown in FIG. 1 has the two singlephase assemblies 24 and 26 vertically stacked, the support means 30 and 32 are preferably vertically spaced and the insulating shaft members 34 and 36 thus have their longitudinal axes vertically disposed. When the single-phase assemblies are horizontally spaced, which is common in pad mounted distribution transformers, the support means 30 and 32 would be horizontally spaced.

The first and second support means 30 and 32 have openings 38 and 40, respectively, which may be used for mounting the switch 12 within the casing 16, such as to the U- frame support 28, and to a bottom support means 42, with suitable nut and bolt assemblies 44 and 46, respectively.

The insulating shah members 34 and 36 are formed of a high strength insulating material which is compatible with the insulating and cooling dielectric fluid in which they are immersed. The laminated plastic materials are suitable, as are molded shaft members formed of synthetic materials, such as a glass filled polyester.

Each of the insulating shaft members 34 and 36 have a plurality of spaced electrical contact members fixed in spaced relation on a common centerline across the length dimension of each of the shaft members 34 and 36. For example, shaft member 34 has a plurality of contact members 50, 51, $3, 55, 57, 59, 6t and 63, plus a plurality of additional contact members which are on the portion of the shaft member 34 which is cut-away in the view of the switch shown in FIG. 2. The electrical contact members 50 are stud members formed of a good electrical conductor, such as copper, and they are fixed through openings disposed through the insulating shaft members such that a portion of the stud extends beyond both of the major surfaces of the insulating shaft members. Thus, for example, electrical contact member 6] has a first end 52 which extends from one of the major sides of the shaft member, which end is adapted to contact or engage another electrical contact member, as will be hereinafter explained, and a second end 54 which extends from the opposite major side of the shaft member, which end is adapted to receive an electrical lead 56, such as by having an opening which starts at end 54. End 54 of contact member 61 may be crimped, such as illustrated at 58, after the electrical lead 56 is inserted into the opening, to form a good mechanical and electrical joint between the conductor stud 6 l and the electrical lead 56.

Six electrical contact studs per insulating shaft, per phase, have been found to provide the versatility required for almost any serievmultiple arrangement, with this specific arrangement being illustrated in FIGS. 1 and 2, but any desired number of contact stud members may be used, as dictated by a specific application. As illustrated in FIGS. 1 and 2, seriesmultiple switch [2 has three groups of six contact studs fixed to each insulating shaft member 34 and 36. The contact studs for each phase on each shaft are spaced to provide the required electrical insulating clearance between them, and the adjacent groups of contact studs are spaced, as required by the insulating clearances and the voltage rating of the switch.

Each of the permanently fixed insulating shaft members of switch 12 have a cooperative movable insulating shaft member disposed in predetermined spaced relation adjacent thereto, which movable shaft member carries a plurality of electrical contact members complementary to the contact members of the fixed insulating shaft member, with certain of the complementary contacts of the adjacent movable and fixed shaft members being in electrical contact with one another. The movable shaft members are movable along their longitudinal axes with a rectilinear motion in response to so tuating means, when it is desired to change the relationship of the complementary contacts.

More specifically, fixed shaft member 34 has a cooperative movable insulating shaft member 60 disposed adjacent thereto, and fixed insulating shaft member 36 has a cooperative movable insulating shah member 100 disposed adjacent thereto. Insulating shaft member 60 is carried by, and guided by, the first and second support means 30 and 32, but it is not permanently fixed to the support means. Insulating shaft member 100, is fixed to the insulating shaft member 60, and moves in unison therewith, as will be hereinafter explained.

Shaft member 60 has first and second major opposed surfaces, two connecting minor opposed surfaces, and a plurality of gear teeth 62 disposed in one of the surfaces near one end of the shaft member, forming a rack. The cooperative insulating shaft members 60 and 34 are disposed relative to one another, such that the major surfaces of the movable insulating shaft member 60 are perpendicular to the major surfaces of the permanently fixed insulating shalt member 34, but it is to be understood that the shaft members may have other configurations For example, the permanently fixed insulating shaft members could have a round or elliptical cross-sectional configuration, as long as they adequately perform the function of holding the contact studs in fixed relation.

The movable insulating shaft member 60 is guided by the first and second support means 30 and 32, such as by guide members 64 and 66, respectively, which members allow only rectilinear movement of the shaft 60, along the direction of the longitudinal axis or center-line of the shaft.

Actuatlng means is disposed to change rotary motion external to the transformer casing, to rectilinear movement of the shaft 60 within the casing. Actuating means 70 includes a pinion gear 72, having shaft members 73 and 75 fixed to and extending axially outward from opposite sides thereof, an operating handle 76, and an intermediate shaft 74 which mechanically couples the operating handle 76 to the shaft 73 fixed to one side of die pinion gear.

The first support means 30 includes a substantially U- shaped bracket member 80 having spaced parallel side portions 82 and 84, and a connecting portion 85. Openings are provided in side portions 82 and 84 through which the shaft members 73 and 75 extend, providing bearings for rotatably supporting the pinion gear 72. Shaft member 73 extends outwardly past side portion 82 for a sufficient dimension for it to be fixed to the intermediate shaft member 74, and the shaft member 75 extends outwardly from side portion 84 for a dimension which is sufficient to provide support for the pinion gear 72 as it is moved along its axis, as will be hereinafter explained, without pulling the shaft 75 all the way through the side portion 84.

A spring member 86 is disposed to encircle shah 73, between one side of the pinion gear 72 and the inner side of the portion 82 of the bracket 80, such that the spring member 86 urges the pinion gear against the inner portion of the side member 84 of the U-shaped bracket member 80, with the width of the pinion gear being sufficient to maintain its teeth in engagement with the teeth 62 of the rack disposed at the end of the insulating shaft member 34, when the spring 86 is compressed and the gear 72 is advanced toward portion 82 of bracket 80.

Operating handle 76 is disposed outside the casing of its associated transformer, and it includes a shaft portion 76 which extends through a dial plate 88, which is also mounted outside the casing, and through the wall of the casing 11 via appropriate sealing means, such as O-ring seals and resilient gasket members, with the seal on opposite sides of the casing wall being shown generally at 90 and 92. While the opening through the wall of the casing I 1 is sealed by means 90 and 92, means 90 and 92 are constructed to allow rotary and rectilinear movement of the shaft member 76 relative thereto.

The operating position of the series-multiple switch 12 is positively determined, and locked against accidental movement, by providing a plurality of spaced openings through the dial plate 88, with each opening corresponding to a different operating position of the switch. For example, as illustrated in FIG. 2, the dial plate 88 will have three openings 94, 96 and 98 for a three position sereis-multiple switch.

The pinion gear 72 has a diameter selected to provide the desired rectilinear movement of shaft member 60 for a predetermined angular rotation of handle 76, with the spacing between the openings in the dial plate 88 being selected accordingly.

The operating handle 76 includes a portion 76" which is substantially perpendicular to the outermost surface or face of dial plate 88, with the end of the portion 76" entering one of the openings in the dial plate 88 when the handle 76 is in the position of one of the operating positions of the switch. Thus, when the handle orientation is as illustrated in FIG. 2, end 76" of handle 76 will extend into opening 94, which is switch position I, under the urging influence of spring member 86. When it is desired to change to switch position 2, the handle 76 is pulled perpendicularly away from the dial plate 88, compressing the spring 86, until end 76" is clear of opening 94. The handle 76 may now be rotated clockwise until end 76" reaches opening 96. Releasing the handle will cause end 76" of handle 76 to enter opening 96, due to expansion of the spring 86, locking the switch I2 in operating position 2. The switch l2 may now be actuated to return to position number I, or to advance to position number 3, by pulling the handle 76 until end 76" clears the opening 96, and rotating the handle in the desired direction. The pinion gear 72 remains engaged with the teeth 62 of the raclt, in any position of handle 76, as the width dimension of the pinion gear and length of its shaft 75 are selected to provide this cooperation. Thus, a predetermined angular movement of handle 76 provides a predetermined rectilinear movement of shaft member 60.

The other fixed shaft in this example, insulating shalt member 36, has a cooperative movable insulating shah member 100, with shaft 100 being fixed to shaft 60, such as with a plurality of insulating spacer members 102 and I04. Therefore, rotation of handle 76 not only moves the insulating shaft member 60, but it also moves the insulating shaft member 100 at the same time.

The movable shaft members 60 and I each have a plurality of spaced, bridging type electrical contact members fixed thereto, such as contact members I I3 and IIS shown fixed to insulating shaft member 60, and contact members 110 and III fixed to the insulating shah member I00. The contact members fixed to the movable insulating shaft members are complementary to the contact studs fixed to the permanently mounted insulating shaft members, and they are formed of a good electrically conductive material which also has a springlike characteristic, such as beryllium-copper. Contact assemblies 110 are constructed to bridge and electrically interconnect two adjacent contact studs on the associated fixed insulating shaft members, with each of the bridging type contact assemblies, such as contact assembly IIO on shaft member 100, including first and second contact plate portions 1 I2 and 114 which may be fixed to the insulating shaft member I00 with any suitable means, such as with a rivet I16 which extends through both contact plates I12 and Ill and through the insulating shafl member I00. The spacing between the inner surfaces of the two plates I12 and I I4 is such that the dimension is slightly less than the outer diameter of the contact stud members on the fixed insulating shaft members, with the contact studs forcing the two plate portions slightly apart when they enter the space between the two spaced plate portions, to provide the required electrical contact over the life of the transformer apparatus.

An exploded perspective view of bridging contact IIO is shown in FIG. 2A, which illustrates a construction for the bridging type contact which has been found to be suitable. In this embodiment, two spaced openings I20 and I22 are provided in the insulating shaft member I00, with the openings extending between the two major opposed surfaces of the shaft member I00. Opening 122 is adjacent the edge of shaft I00 which faces the stationary contact members, and opening 120 is adjacent the opposite edge of the shaft. A spring or resilient member I24 is disposed in opening 120 and held in place by the contact plate portions I12 and 114 when they are fixed to the shaft by the rivet I16. The spring member I24 urges the contact plates I12 and I14 slightly apart on one side of the rivet I16, and slightly together on the other side where they contact the stationary contact studs. When contact I I0 is engaged with contact members from the fixed shaft members, the plate portions are spread apart slightly, compressing the spring I24 to maintain the required electrical contact between the bridging contact member I I0 and two of the contact studs which are connected to the electrical leads of the transformer winding.

The bridging type contacts have a dimension parallel with the longitudinal axis of its associated insulating shaft member, selected such that the bridging contact will successively bridge two difl'erent adjacent contacts, from position to position across the switching range of the series-multiple switch. For example, in switch position I, bridging contact I13 electrically interconnects stationary contact studs 50 and 51, and bridging contact II! electrically interconnects contact studs 53 and 55. In switch position 2, bridging contact 113 electrically interconnects stationary contacts SI and $3, and bridging contact IIS electrically interconnects contacts 55 and 57. In switch position 3, bridging contact 113 electrically interconnects contact studs 53 and 55, and bridging contact 1 I5 electrically interconnects contact studs 57 and 59.

The operation of the series-multiple switch I2 may best be illustrated by considering its application to a specific seriesmultiple arrangement, with FIGS. 3, 4, 5 and 6 illustrating the connection of the series-multiple switch I2 in a T-T arrangement, shown generally in FIG. I. FIG. 3 is a partially schematic and partially diagrammatic representation of transformer I4 and switch 12, with switch 12 being in operating position I which interconnects the transformer windings in a multiple or parallel arrangement, as illustrated in this schematic diagram of FIG. 6. and FIG. 5 is a partially schematic and partially diagrammatic representation of transformer 14 and switch I2, with switch I2 being in operating position 2 which connects the transformer windings in a series arrangement, as illustrated in the schematic diagram of FIG. 6.

More specifically, the single-phue assembly 24 includes a plurality of high voltage winding sections I30, I32 and I34, which winding sections are connected in series or in parallel, by a portion of the series-multiple switch I2. As hereinbefore explained, the series-multiple switch 12 includes two fixed insulating shaft members each of which have three groups of six contact studs disposed thereon. The first group of contact studs on insulating shaft member 34 are numbered 50, SI, 53, 55, 57 and 59, and the first group of contact studs on insulating shafl member 36 are numbered 50', SI, 53', 55', 57' and 59'. A jumper 204 is connected between contact studs SI and 53, a jumper 204 is connected between contact studs 51' and 53', and a jumper 206 is connected between contact studs 53' and 57. Winding section 130 has first and second terminals 134 and 136, with one terminal 134 being connected to high voltage insulating bushing 19 via a protective link 100. Terminal 136 of winding section 130 is connected to terminal 53'.

Winding section 132 has terminals 138 and 140, with terminal 138 being connected to contact stud 55, and terminal 140 is connected to contact stud 55'. Winding section 134 has terminals 142 and 144 disposed at its ends, and an intermediate tap or terminal 146, with terminal I42 being connected to contact stud 51, terminal 144 being connected to contact stud 50' and also to a terminal l90 which is the midtap of the single phase assembly 26, and the intermediate tap M6 is connected to contact stud 57'. Contact stud 50 is connected to high voltage insulating bushing 19 via a protective link 202. In this particular example, the series-multiple switch [2 is used as a two-position switch, and contact studs 59' and 59 are free of electrical connections.

The second single phase assembly 26 has six high voltage winding sections 150, 152, 154, 156, 158 and 160, with the first three winding sections 150, 152 and 154 being connected in series, or in parallel through the second group of contact studs on the fixed insulating shaft members 34 and 36, with these winding sections being connected in series or in parallel between high voltage bushing assembly 20 and the mid'tap terminal 190.

The remaining winding sections of single-phase assembly 26, winding sections 156, 158 and 160, are connected in series or in parallel through the last portion or group of contact studs on the series-multiple switch assembly 12, connecting these winding sections in series or in parallel between high voltage bushing assembly 21 and mid-tap terminal 190.

In the operating position of series-multiple switch 12 shown in FlG. 3, the bridging contacts 113, 115, 110 and Ill interconnect the winding sections 130, 132 and 134 in parallel, and the remaining bridging contacts connect windings 150, 152 and 154 in parallel, and windings 156, 158 and 160 in parallel as illustrated more clearly in the schematic diagram of the transformer 14 shown in FIG. 4.

FIG. is a partially schematic and partially diagrammatic view of the transformer 14 and switch 12, with the switch 12 being in operating position 2, which connects the various winding sections in series. FIG. 6 is a schematic diagram of transformer l4, which more clearly illustrates the series connection of the winding sections in switch position 2.

in summary, there has been disclosed a new and improved series-multiple switch which may be manufactured for a relatively low cost without sacrificing durability and reliability, and which may be mounted to take advantage of the space normally available adjacent the windings, to reduce the lead length from the windings to the switch without requiring an increase in the casing dimensions because of the switch. The disclosed series-multiple switch may be easily constructed to have the desired number of switch positions, and the desired number of phases, and the in-line construction of the switch eliminates the necessity of interconnecting a plurality of decks or separate contact assemblies via mechanical linkages or other mechanically complex arrangements.

1 claim as my invention:

1. An electrical switch adapted for mounting within the casing of an electrical transformer, comprising:

first and second spaced support means,

a first insulating shalt member fixed to said first and second support means,

a plurality of first electrical contact members fixed to said first insulating shalt member in spaced relation on a common center-line,

a second insulating shaft member carried by said first and second support means, said second insulating shaft member being movable relative to said first and second support means, a plurality of second electrical contact members fixed to said second insulating shaft member in spaced relation on a common center-line, parallel to the center-line on which said first electrical contact members are disposed, and spaced therefrom to cause electrical contact between certain of said first and second electrical contact members,

each of the second electrical contact members including two separate spaced metallic portions oppositely disposed on said insulating shaft member, the first electrical contact members engage the second electrical contact members by entering the space between the two spaced metallic portions and forcing them slightly apart,

and actuating means disposed to move said second insulating shaft member rectilinearly when it is desired to change the relationship of said first and second electrical contact members.

2. The electrical switch of claim 1 including a third insulating shah member fixed to the first and second support means, a plurality of third electrical contact members fixed to said third insulating shah member in spaced relation on a common center-line, a fourth insulating shaft member fixed to said second insulating shaft member, and a plurality of fourth electrical contact members fixed to said fourth insulating shaft member in spaced relation on a common center-line, each of said fourth electrical contact members including two separate spaced metallic portions oppositely disposed on said fourth insulating shalt member parallel to the center-line on which said third electrical contact members are disposed, and spaced therefrom to cause electrical contact between certain of said third and fourth electrical contact members, the relationship of said third and fourth electrical contact members changing in response to the actuating means.

3. The electrical switch of claim 1 including a casing having side wall, bottom and top portions, a liquid dielectric disposed in said casing to a predetermined level, and a magnetic corewinding assembly disposed in said casing and immersed in said liquid dielectric, wherein the electrical switch is disposed in said casing, with its first and second electrical contacts disposed below the predetermined level of said liquid dielectnc.

4. The electrical switch of claim 3 wherein the magnetic core-winding assembly includes a plurality of single-phase core-winding assemblies disposed side-by-side relative to the bottom portion of the casing, and the first and second support means are horizontally spaced.

57 The electrical switch of claim 3 wherein the magnetic core-winding assembly includes a plurality of single phase core-winding assemblies disposed in a vertical stack, relative to the bottom portion of the casing, and the first and second support means are vertically spaced. 

1. An electrical switch adapted for mounting within the casing of an electrical transformer, comprising: first and second spaced support means, a first insulating shaft member fixed to said first and second support means, a plurality of first electrical contact members fixed to said first insulating shaft member in spaced relation on a common center-line, a second insulating shaft member carried by said first and second support means, said second insulating shaft member being movable relative to said first and second support means, a plurality of second electrical contact members fixed to said second insulating shaft member in spaced relation on a common center-line, parallel to the center-line on which said first electrical contact members are disposed, and spaced therefrom to cause electrical contact between certain of said first and second electrical contact members, each of the second electrical contact members including two separate spaced metallic portions oppositely disposed on said insulating shaft member, the first electrical contact members engage the second electrical contact members by entering the space between the two spaced metallic portions and forcing them slightly apart, and actuating means disposed to move said second insulating shaft member rectilinearly when it is desired to change the relationship of said first and second electrical contact members.
 2. The electrical switch of claim 1 including a third insulating shaft member fixed to the first and second support means, a plurality of third electrical contact members fixed to said third insulating shaft member in spaced relation on a common center-line, a fourth insulating shaft member fixed to said second insulating shaft member, and a plurality of fourth electrical contact members fixed to said fourth insulating shaft member in spaced relation on a common center-line, each of said fourth electrical contact members including two separate spaced metallic portions oppositely disposed on said fourth insulating shaft member parallel to the center-line on which said third electrical contact members are disposed, and spaced therefrom to cause electrical contact between certain of said third and fourth electrical contact members, the relationship of said third and fourth electrical contact members changing in response to the actuating means.
 3. The electrical switch of claim 1 including a casing having side wall, bottom and top portions, a liquid dielectric disposed in said casing to a predetermined level, and a magnetic core-winding assembly disposed in said casing and immersed in said liquid dielectric, wherein the electrical switch is disposed in said casing, with its first and second electrical contacts disposed below the predetermined level of said liquid dielectric.
 4. The electrical switch of claim 3 wherein the magnetic core-winding assembly includes a plurality of single-phase core-winding assemblies disposed side-by-side relative to the bottom portion of the casing, and the first and second support means are horizontally spaced.
 5. The electrical switch of claim 3 wherein the magnetic core-winding assembly includes a plurality of single-phase core-winding assemblies disposed in a vertical stack, relative to the bottom portion of the casing, and the first and second support means are vertically spaced. 